Finely divided metallic compounds and process therefor



R. H. EAGLES FINELY DIVIDED METALLIC COMPOUNDS AND PROCESS THEREFOR Filed Jan. 11. 1927 FIG 11 REG1NALDH.EAG LE5.

IN VENTOR A TTOENEV Patented Oct. 27, 1931 UNITED STATES PATENT OFFICE FINELY DIVIDED METALLIC COMPOUNDS AND PROCESS THEREFOR Application filed January 11, 1927. Serial No. 160,392.

My invention relates to the production of finely divided metallic compounds and more particularly to the production of finely divided oxides of lead and zinc.

t is an object of the present invention to provide such metallic compounds in a form suitable for use as pigments. It is a further object to produce pigments of improved covering power, when used for paints, and such as will impart a much increased resistance to wear when they are used as fillers for rubber products.

It is well known that finely divided solids may be produced either by the condensation of sublimed vapors as in the manufacture of sublimed lead, or by the condensation of the solid products of combustion from any burning vapors as in the manufacture of zinc oxide. The usual method of manufacture of these compounds as at present practiced is to permit the highly concentrated vapor to condense'or precipitate in a more or less unrestricted volume and to collect the resulting solid particles in a somewhat cooled condition by entraining with a fabric of some kind (such as is done in the bag process for collecting zinc oxide), or, by deposition in settling chambers, or, by electrostatic precipitation.

It has been the usual practice in present processes to bring the vapors to a concentrated condition just prior to the precipitation or condensation when the molecules or atoms are in transition from the gaseous to the solid i state. This has a tendency to force the particles to determine into spheroidal form, and since they cool and pass on into the collection apparatus in this form, they remain thus in the finished product.

The eficiency of any pigment or filler is largely dependent upon the fineness of division of its particles and the shape thereof. In paints, for example, the surface area represented by a given volume of particles deter- -mines its relative value in covering power.

A particle of irregular contour will present more covering power efiiciency than a spheroidal particle of the same relative size and specific gravity. Similarly, in the reenforcement of rubber and rubber products to produceresistance to wear, a particle of irregular contour will anchor into the rubber with better effect than a smooth surfaced or spheroidal particle, and will have a more beneficial effect.

I have discovered that many of the well known pigments and fillers may be produced in a form in which the particles are much more finely divided and of much more irregular shape than is the case with similar prodso ucts made according to present processes. I have further discovered a process of precipitation and collection of metallic compounds whereby the size and shape of the particles can be controlled during manufacture so as to result in a product of greater utility than at present is the case.

In applying my invention, I begin with any solid or liquid containing the desired metal that can be volatilized into a gaseous form that is either condensible per se, or, that can be made condensible by total or partial combustion in the presence of oxygen. I volatilize the metal and dilute the vapors with another gas in greater or less proportions thus varying the concentration of the metallic vapors. My means hereinafter described I cause these solid particles to deposit by impingement against a relatively cooler surface positioned in or near the region of precipitation or condensation. The deposited particles can then be removed by any suitable means.

My invention may be more clearly understood from the drawings to which reference is now made.

Fig. I represents schematically a suitable apparatus for carrying out the process of my invention applied to the manufacture of zinc oxide.

Fig. II represents schematically the deposition chamber of this apparatus viewed at right angles to the view in Fig. I and illustrates one method by which the deposited or collected product may be conveyed out of the apparatus.

In Fig. I, A is an ordinary furnace retort.

A bed of fuel, y, heats a charge of metallic zinc introduced into the retort, 2. The retort is connected with a pipe or duct, B, which 0 i extends into the deposition Chamber, C supplied with atmospheric air. A dilution duct, D, adapted to admit gases for the dilution of the metallic vapors connects with the duct, B, the admission of the diluting gases being controlled. by the valve, E. Afiixed to the portion of the duct, 13, which is Within the depositibn chamb r; Q, is; a ow at bu ner tips, F. A metallic impingement plate, G, is positioned above the tips, F. conveniently beoi's'teel and may be'somounts ed as to be actuated by a slow reciprocating motion through a mechanism consisting-"of the geared Wheel, H, and the gear, l -on the impingement plate, .G Scrapers, K, contactw t the impi g men p ate, on, it nder ide; r moun ed. so a he remove. the deposi ed at r ah I have sh wn the am na add tional u bleeding f om the deposition chamber, C, to the fabric bags,

Methane dot ed ine te ndica e a means i o jf condt cti ng away the zinc LEQW hi h;

a aghave es aped mp ngem nt with the pla whi h may bet leete hi P er- 2 ipnat n n olid v pa l s as. tax ein; he

bags, a Well-known P EQYlSVlQIL or lect ic lly heating; he; ducts, B, nd: I)", s

' maideh tha e t gpoil O I;n; n, I, havelshownt s hemati ally right melee he iew thereo shown n F I. In this'view ilLbe noted that the per i no v he duct, B,,Withinthe depen- Q! an lf n; imigi gem nt pla. abovet e rners-U B lowea nd, to c rry t; way,

I The p r ion o preeess egins wins the volatilizat nn 0t amate ahsuch m tall c. o m; his s efieet rl lls l fig lee o t fur-1 A; Hea is urn shed; by; the

burni g; le hy h filrnace-an lais mains tained; a mpera ure bove, 700; O; A

charge of'pure metallic zinc is placed inlthei n tea aaahdah ile li Insteadnfi .punemetal- {791E311 e her: Z1119, cpmp nnds he used:

or the charge may be of zinc or e in; which easa he ore he: redncectte the me al; and tan rizerli the same] operation The. resuiting vapors; arethen -carniedi by; tl'lGlIfQWIl;

pressure into and through the duct, 135,01:

theisp gress may be aided byrai carrying gas admi ed; hro gh the:v valve, E1, on by: a Ql'; .d-I;flfi

important: feature ofi' the invention "is the control: oifgthe iQOIH'BDl IELtlOIIT'Of theizinc" vapors Which are to be precipitated. or coni-tm densed, inonder tofproduce;the optimum conditions. b aining hersmallestsized; ar, t cl s h he ultima eprodu *I; ccomplish;

we hisg fliln ie wt he:me allie aporstwitha ably,- duet-to; the factthat tliey have been This plate, Gr, may

tible tn other gases, the proportion of the diluting gas to the metallic vapors governing the size of the-particles in the finished product. The dilution may be efi'ected in anumber of Ways. An inert gas, for example, may be admitted tothe duct, B, from the dilution duct, D, through the vaLve.,E. Dilution may be effected; also by providing a Very. largenumber of orifices on the portion of the'duct, B, that is Within the deposition chamber C'.

A Veryefieeti've dilutionoceurs-, for instance,

Where the duct, B, is a pipe of about, 10 inches diameter," and" is divided into a number bersufiicient to accommodate several hun- Stent an bastion. of the mixed gasiand zinc. vapors, in;-

t: gas,; I introduce a 'c'oinhus e, the, valve, E. Ehi-s'; servesthe. double p ilu ion QiHClE of? assisting in a the combustion;

Theeoils 94,.W01111d3abtint: theducts,B and D, semteitoimaginhaiin charges and vapor" mix-- ture. air a; tempenatune above the'volatili'z'a iomtemperature of therzine until; it reaches theibimnersy F,.in' the deposition: chamber, This: heatihgr pnevents: any precipitation or condensatiomwitlnimthe duct", Bi.

eEheLgaseous; mixture passes through the duct,B,.tolthe bnrners,.F,. Where'itis ignited andi the vapors: the? mixture/ are thus: oxidized. While the zinc oxide particles-- are. i-mthetransition state from gas to 'selid 1n the-region between; the burners and theplahe Gr; they: impinge with considerable irelocihy against: theplate, Whiclrisrela-- timely eoolen ands uponwhich: the solid particles deposit. The" plate, moves'slo-Wly hack andt'fonth O'VBIr the, burners, F, beingactuatediby the necipnocati ng gears, H and; I, and; asit-movesthescrapers, which are stationarygscrape the zinc ox-ide firom the plates, 1G: llhexonirle then fallstothebottom oftheLdepomt chamber orinto the conveyors,

N;atthe-bottom asishownin Fig; If. 7 The produetthusl-obtained is oi a very finey; diivi-dedi nature, the particles being far 7 moreminutexthan isv the case withtheproduct' ohthapresent processes; Furthermore; the depositedrparticles have an irregulav shape ihsteadi oi the: spheroidalishape 1 of the prod-- nctxof'the presentiprocesms, which is'prolou'rpose of providing: a; suitable caused to impinge violently against the relatively cooler surface of the steel plate at the instant of condensation from the gaseous t0 the solid state.

As a certain amount of the precipitated solids will escape around the plates, G, without impinging thereon, suitable means for their collection may be provided, such as the duct, L, and the bags, M.

While I have illustrated my invention by showing its application to the production of zinc oxide, it is to be understood that it is equally applicable to the production of lead oxide and other finely divided metallic compounds.

Having thus described my invention what I claim is 1. The process of producing irregularly shaped metallic compound particles which comprises diluting metallic vapors with a suitable gas, burning said diluted vapors and causing the products of such combustion to impinge upon a relatively cooler surface while said products of combustion are in a state of transition from the gaseous to the solid state.

2. The process of producing finely divided metallic compounds which comprises the burning of a diluted metallic vapor, controlling the size of the particles of the product by the proportions of the diluent to the metallic vapors in the mixture and causing said particles to assume an irregular shape by depositing them by impingement against a relatively cooler surface positioned in the region of condensation of said particles.

3. The process of producing finely divided zinc oxide which comprises the vaporization of zinc, the dilution of said vapors with another gas in such manner as to control the concentration of the metallic vapors so as to attain the optimum conditions for producing the smallest sized particles in the finished product; burning said vapors and causing the products of said burning to impinge against a relatively cool surface in the region of condensation of the metallic vapors to the condition of solid particles and giving said particles an irregular shape by such impingement.

In witness whereof, I have subscribed my name hereto this 7th day of January, 1927.

REGINALD I-I. EAGLES. 

